Laser oscillators utilizing optical fiber are widely used. These laser oscillators utilize excitation light that is oscillated by a light source and oscillate laser light using optical fiber. The optical fiber that is used in these laser oscillators is formed by fluoride glass such as ZBLAN glass doped with a laser active material such as erbium, for example.
Here, the laser active material that is included in the optical fiber generates heat due to absorbing excitation light, possibly resulting in the optical fiber being damaged by the generated heat. In particular, fluoride fiber has low heat resistance compared with quartz fiber.
In view of this, a cooling device for cooling the optical fiber has been proposed. A metal heat dissipation member is used to bring the optical fiber in close contact with the surface of a heat sink that is cooled by a coolant. The metal heat dissipation member is formed as a thin film having tackiness, and is provided so as to cover an entirely of the optical fiber.